1. Field of the Invention
An object of the present invention is a tin-soldering machine with an automatic wave barrier for printed circuit boards.
2. Description of the Prior Art
In electronic industries, where printed circuit boards are mass produced, components are soldered by the so-called "wave" soldering process in which a turbine maintains a constant output of molten lead-tin alloy that flows out over a spout with a specific shape.
The shape of the surface of the molten alloy, its flowing-out speed and its cleanness are major factors that determine the quality of the solders.
The geometry of the electronic board is also a determining factor: ideally, the board is flat and, in its translational motion, it approaches a rectilinear generating line of the surface of the molten alloy.
In practice, boards are not flat and have a tile shape which becomes accentuated with increasing width. The molten metal generating line is not rectilinear either, and its surface may be spoiled by dross.
It will be understood that, if the board to be soldered has a tile shape with downward convexity, there is a very great risk that, during the approach, the molten metal will flood the components side of the board which will then be irretrievably lost. If a compromise setting is attempted to avoid this problem, there is the risk that the components will not be soldered.
These reasons lead to the use of costly remedies, among them:
the addition of stiffeners to the electronic board itself. If the board contains power elements, the rigidity of the metallic radiators could be taken advantage of;
or, more generally, a soldering frame is used, in which the circuit is confined and which combines the functions that the electronic board cannot fulfil by itself, especially the wave barrier function.